Plastic internal screen

ABSTRACT

A sieve assembly for a sifter consisting, in addition to the usual sieve cloth, of only a unitary, one-piece carrier connectable to the sieve cloth, said carrier functioning as a container for the sieve cleaning means whereby the conventional sieve frame and spacer are eliminated.

United States Patent [72] Inventor 2,269,289 1/1942 Schifflin 2,395,1382/1946 Nicholls 2,587,498 2/1952 Marsh 2,829,772 4/1958 Landes 3,170,8752/1965 3,390,771 7/1968 Wehner......,,........,.. 1,799,416 4/1931Gi1lerpie....................... 2,576,746 11/1951Barnes..........................

Charles S. Pennington. Lombard, Ill.

[211 App]. No. 787,866

Dec. 30, 1968 [45] Patented Feb. 23, 1971 Blaw Knox Company Pittsburgh,Pa.

[22] Filed [73] Assignee FOREIGN PATENTS 7/1879GreatBritain.............,..

Primary Examiner- Frank W. Lutter Assistant ExaminerRobert Hal PLASTICINTERNAL SCREEN 4 Claims, 3 Drawing Figs.

per Attorney-Parker Carter & Markey [50] Field 332, 379, 385, 387;210/consulted ABSTRACT: A sieve assembly for a sifter consisting, inaddition to the usual sieve cloth, of only a unitary, one-piece carrierconnectabl e to the sieve cloth, said carrier functioning as a containerfor the sieve cleaning means whereby the conven- S T N m MA 3 mm mA m nH N U m h.

209/382 tional sieve frame and spacer are eliminated.

PATENTEU FEB23 49m sum 1 OF 2 PLASTKC INTERNAL SCREEN This inventionrelates generally. to sizing or sorting apparatus used in industrialprocessing, and more specifically to sifting or screening structure forsifting, screening, bolting, rebolting, grading, scalping, separating orclassifying depending on the industry and the point in the process atwhich the operation is performed. For purposes of illustration theinvention will be described as applied to a sifter of the type in whicha reciprocal and/or rotary motion is imparted to one or more siftingstages within a particle-tight enclosure having inlet and outlet means.

BACKGROUND OF THE INVENTION In prior constructions of the type describedgenerally above each sifting stage has been composed-of a plurality ofcomponents, each of which has to be carefully constructed and assembled.Specifically, a single sieve stage must be carefully built up from asieve cloth, a sieve frame, (which may function as a spacer as well as asupporting frame), a carrier screen,

, and a plurality of cloth cleaners, such as rubber balls which arecontained in a plurality of compartments formed when the sieve cloth,frame, and carrier screen are in assembled relationship.

By contrast, by virtue of the construction of the present invention,separate sieve frames and carrier screens are eliminated, along with theattendant manufacturing and assembling intricacies. The result is asieve assembly which is more economical to manufacture and assemble thanprior constructions, and is equally, or more, efficient for its intendedpurpose than prior constructions.

SUMMARY OF THE INVENTION Accordingly an object of the invention is toprovide a sizing and/or sorting assembly which is more economical tomanufacture and assemble, and is of equal or greater, efficiency for itsintended purpose than prior constructions.

Another object is to provide a sizing and/or sorting assembly havingonly two basic components in addition to conventional cloth cleaners,said assembly being substantially lighter in weight than priorconstructions yet having adequate strength for its intended purpose andbeing shock resistant and flexible.

Yet another object is to provide a sieve assembly as above describedwhich lends itself to mass production forming techniques as contrastedto prior constructions which required substantial hand labor, andthereby custom work on each sieve assembly.

Yet a further object is to provide a single stage sieve assembly havingthe aforementioned characteristics and, in addition thereto, is capableof adaptation to a modular system whereby only one, or at most a veryfew, structurally different sifting assemblies need be stocked by themanufacturer and/or user to provide a sifting apparatus having-anydesired number of sifting stages.

Other objects and advantages of the invention will become apparent fromthe following description of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT The invention is illustrated more orless diagrammatically in the accompanying FIGS. wherein:

MG. 1 is an exploded, perspective view of a single stage sift ingassembly comprising the present invention;

FIG. 2 is a longitudinal sectional view to a larger scale than FIG. lwith parts broken away and others shown in section for clarity; and

FIG. 3 is a transverse side view of the sieve carrier of FIG. 2.

Like reference numerals will be used to refer to like parts from FIG. toFIG. in the drawings.

Referring first to FIG. 1, a single stage sifting assembly is indicatedgenerally at 10. Although the term sifting has been applied to theillustrated structure, it will be understood that within the skill ofthe art the terminology will vary, depending upon the industry to whichthe invention is applied and the point in the particular process atwhich the operation is performed. The term sifting" is used herein andin claims as a synonym for other well recognized terms in dissimilararts for substantially the same operation which is the sizing or sortingof articles which, in an initial condition, are of dissimilar size. Theterms screening, bolting, rebolting, grading, scalping, separating orclassifying and possibly others may be applied to the process andapparatus in addition to sifting."

The sifting assembly includes a sieve structure indicated generally at12. The sieve structure 12 includes a sieve cloth 14 which may be madeof any suitable material, such as wire, standard tinned or alloyedmetals, natural silk, nylon or grit gauze. The longitudinal edges of thesieve cloth 14 are received between strips 16, only the upper one of apair of which is illustrated in the drawing, which makes possible thestretching of the sieve cloth to place it'under suitable tension.Transverse edge strips are indicated at 18, again only the upper one ofthe pair beihg illustrated. A- plurality of bendable flaps indicated at20, 22 extend outwardly beyond the peripheries of longitudinal andtransverse edge strips 16 and 18.

A carrier for sieve cleaner means is indicated generally at 24. Thecarrier, which serves the dual function of a spacer and a means forproviding sieve cleaning means, is a unitary onepiece, molded plasticconstruction. Specifically, the carrier is composed of longitudinalsidewalls 26 and transverse sidewalls 28 which terminate at their upperedges in peripherally continuous, outwardly extending flanges 32,34respectively. The carrier is divided into a plurality of internalcompartments by longitudinally extending ridge structures 38, 40, themaximum elevation of which is no greater than the elevation of the uppersurfaces of flange 32,34 which are in abutting contact with the undersurface of the sieve structure 12, when in assembled relationship, asbest illustrated in FIG. 3. The three longitudinal compartments formedby ridges 38,40 and longitudinal sides 2am further subdivided intosmaller compartments by generally transversely extending ridge means42,44 and 46. Ridge means 42-46 project upwardly to the same elevationas longitudinal ridges 38,40, to provide support for the sieve structure12. By terminating short of the upper surface of flange 32,34, at theintersections with sidewalls 26,28 and ridge structures 38,40 thetransverse ridges 42,44 and 46 provide greater structural rigidity tothe carrier, eliminate corner surfaces which might tend to becomeclogged with material undergoing processing, and contribute to thereduced weight of the structure as contrasted to prior constructions.

The bottom of the compartments are formed by a plurality of small,generally transversely extending ribs, 48, and, in this instance,generally longitudinally extending ribs, 50, which intercept thetransverse ribs 48. It should be observed from FIG. 1 that thetransverse ribs 48 are spaced apart a distance sufficient to provideeasy passage therethrough of the unders which drop through sieve cloth14.

It will be noted that the carrier lends itself well to mass productionforming techniques, such as by vacuum forming since the entire structuremay be formed as one piece. lf desired, the carrier in its as formedcondition may include a solid sheet material covering spaces formedbetween ribs 40, this material being easily removed in a single cuttingoperation.

Sieve cleaning means are indicated at 52, the cleaning means in thisinstance consisting of a pair of balls contained in each compartment,said balls having the characteristics, with respect to compressabilityand distortability, of rubber. It should be understood of course thatwithin the scope of the invention any suitable material may be used forthe balls, and such materials are today well known in the art. Likewise,only 4 or more than 2 balls may be used, and in practice as many as 4 to6 have been employed.

As best illustrated in FIG. 3, for example, the sieve cloth contact onewith the other. The flaps, 20,22, are bent about a line of weakness 54,or 56 inwardly toward flanges 32,34. Spring clips 58, or other suitablemeans, may be further employed to securely fasten the sieve cloth to thecarrier.

The single stage sieve assembly just described may be placed within atray structure 60 which includes an unbroken cloth l4 and carrier 24. Itwill be noted that the surface 62 is, in this instance, formed fromessentially two pieces of sheet material 66, 68 which meet at junctionline 70 which causes discharge of material toward outlet 64.Longitudinal and transverse walls 72,74 may be of any desired height.Another outlet means is indicated at 76 to receive the overs which aredischarged from sieve cloth 14. ln this instance another dischargeoutlet means is indicated at 78 at to receive material which may havebeen discharged from a sieve assembly located at one, two or more stagesabove the illustrated stage.

it will be understood that one or more stages may be assembled one withthe other depending upon the number of sizing or sorting operationsdesired. As is well known in the art, a particle-tight cover may beemployed above the uppermost stage which, when clamped to the lower trayforms a substantially airtight or at least particle-tight compartment. Acover will of course have inlet means which may for example consist of aflexible sleeve to accommodate relative movement between theabove-described structure and a stationary feed source.

The above assembly, when incorporated in a suitable motive platformwhich may for example move either in a reciprocal or rotary motion, or acombination of said motions, will efficiently perform the desiredsorting and sizing operations.

The use and operation of the invention is as follows.

A carrier means 24 for the sieve cleaning means 52 may be formed fromany convenient material by any convenient method. Preferably plastic, ora material having the characteristics of plastic with respect to shockabsorption, strength, and flexibility, may advantageously be used. Thestructure may be formed by any suitable means, such as vacuum forming,and if desired, techniques of that art such as casting a continuousbottom surface, may be employed. in any event, a unitary, one-piececonstruction has been provided which serves the dual function ofproviding structure for containing sieve cloth carrier cleaning meanswhen in assembled relationship with sieve cloth l4, and spacing thecarrying surface formed by ball supporting ridges 48 any desireddistances beneath sieve cloth 14. The sieve 12, which may be of anysuitable construction, is secured to the outwardly extending flanges ofthe carrier by flaps 20, 22 and securely fastened by spring clips orother suitable securing means 58.

When the above-described sieve assembly, which forms in effect a singlestage sifting operation, is placed in a support structure, which may forexample be a bottom tray 60, and then given a rotary and/or reciprocalsifting motion, a sifting action is performed as is well known in theart. Overs work their way to discharge outlet 76 by virtue of the factthat the entire assembly may be slanted toward said discharge outlet. Itwill be noted for example that longitudinal wall 73 is of a lesservertical height than longitudinal wall 75.

Although a preferred embodiment of the invention has been illustratedand described, it will be at once apparent to those skilled in the artthat further modifications may be made within the skill of the art.Accordingly, the scope of the invention should be limited not by thescope of the foregoing description, but solely by the scope of thehereinafter appended claims when interpreted in the light of thepertinent prior art.

lclaim: 1. In combination in a sieve assembly, a sieve structure, saidsieve structure comprising:

a flexible member having apertures therein through which material to betreated may be passed; edge bounding means forming a framework to whichthe flexible member is mounted and providing a planar rigidity to theflexible member; and a sieve structure cleaner means carrier, saidcarrier comrrsm pair of end wall means and a pair of sidewall means,said end wall means and sidewall means terminating at their upper edges,in a common plane, flange means extending outwardly from the upperedges, said flange means lying in a common plane whereby the uppersurface of said flange means may be disposed in planar, abutting contactwith the lower surface of the edge bounding means of the sievestructure, first ridge means extending from one of said wall means inone of said pairs of wall means to an opposite wall means, the uppersurface of said first ridge means providing abutting support for thesieve structure disposed thereabove, second ridge means extending fromone of said wall means in the other of said pairs of walls means to anopposite wall means, at least a portion of said second ridge meansproviding abutting support for the sieve structure disposed thereabove,apertured bottom means, i said wall means, ridge means, and bottom meansbeing unitarily formed and forming a plurality of five-sidedcompartments, each of said compartments tapering inwardly in thedownward direction, said sieve structure cleaning means carrier beingcomposed of plastic, means for connecting the sieve structure to thecarrier whereby six-sided compartments are formed, sieve cleaner meanswithin each of said six-sided compartments, means for preventing buildupof treated material at the junctions of the first and second ridge meansin the compartments, said buildup prevention means comprising adepression formed in the second ridge means at their junctions with thefirst ridge means, and the depth of said depressions being less than theheight of the sieve cleaner means contained in said compartments.

2. The combination of claim 1 further characterized in that the sievecleaner means are a plurality of balls, within the sixsidedcompartments.

3. The sieve assembly of claim 1 further including tray means having asurface underlying the carrier which is unbroken except for outlet meansfor unders which pass through said carrier.

4. The sieve assembly of claim 3 further including:

cover means adapted to enclose the assembled sieve assembly inparticle-tight relationship with the tray means; said cover means havingan inlet thereto for the reception of material to be treated; and meansfor imparting sifting movement to the sieve assembly.

1. In combination in a sieve assembly, a sieve structure, said sievestructure comprising: a flexible member having apertures therein throughwhich material to be treated may be passed; edge bounding means forminga framework to which the flexible member is mounted and providing aplanar rigidity to the flexible member; and a sieve structure cleanermeans carrier, said carrier comprising; a pair of end wall means and apair of sidewall means, said end wall means and sidewall meansterminating at their upper edges, in a common plane, flange meansextending outwardly from the upper edges, said flange means lying in acommon plane whereby the upper surface of said flange means may bedisposed in planar, abutting contact with the lower surface of the edgebounding means of the sieve structure, first ridge means extending fromone of said wall means in one of said pairs of wall means to an oppositewall means, the upper surface of said first ridge means providingabutting support for the sieve structure disposed thereabove, secondridge means extending from one of said wall means in the other of saidpairs of walls means to an opposite wall means, at least a portion ofsaid second ridge means providing abutting support for the sievestructure disposed thereabove, apertured bottom means, said wall means,ridge means, and bottom means being unitarily formed and forming aplurality of five-sided compartments, each of said compartments taperinginwardly in the downward direction, said sieve structure cleaning meanscarrier being composed of plastic, means for connecting the sievestructure to the carrier whereby six-sided compartments are formed,sieve cleaner means within each of said six-sided compartments, meansfor preventing buildup of treated material at the junctions of the firstand second ridge means in the compartments, said buildup preventionmeans comprising a depression formed in the second ridge means at theirjunctions with the first ridge means, and the depth of said depressionsbeing less than the height of the sieve cleaner means contained in saidcompartments.
 2. The combination of claim 1 further characterized inthat the sieve cleaner means are a plurality of balls, within thesix-sided compartments.
 3. The sieve assembly of claim 1 furtherincluding tray means having a surface underlying the carrier which isunbroken except for outlet means for unders which pass through saidcarrier.
 4. The sieve assembly of claim 3 further including: cover meansadapted to enclose the assembled sieve assembly in particle-tightrelationship with the tray means; said cover means having an inletthereto for the reception of material to be treated; and means forimparting sifting movement to the sieve assembly.